Fondant Question

I am making a sheep cake for my daughters 1st birthday. I had planned on doing this the day before. I just read somewhere that as fondant sits the colors darken (when coloring it) So should I color it the day before I plan on making the cake so that I know I am getting the right colors?

Thanks. I have been planning this party since she was 6 months old. Now I am done and am glad to hear there is something to do earler!!!! Thanks everyone. Now I have decided to get real brave and try to make the cake match her wrapping paper. Wish me luck!!!